Guys give me a clue.

I appeared for GMAT in September 2010 score 650. Never started the application process feeling the disappointment as I was scoring well enough in Mock tests ie 690-710 in Kaplan.
Now some how I feel motivated again to appear in end July.

Basically I am a Civil Engineer with 4 years work experience, and decent if not excellent extra curricular activities. The profile is not very exciting as I do not have any international exposure, no community service etc.
And most importantly a steady decline in my academic marks.
Hence to improve all this only option is score higher than 650 certainly possibly around 720-730.

My question is can any one give me a tentative marks for ISB Hyd which is the only college I intend to target. Certainly no body knows the cut offs but then I just need an tentative fig.?

Also will me being an Civil engg be any advantage or disadvantage or be just any other application because you see Site based Civil Engineers rarely appear for GMAT MBA etc. They only keep on piling work exp for better options in career.

Can I project my Civil Execution experience as my USP in my applications? Stating it shall add diversity to the crowded IT guys?

Regards